1. Field of the Invention
The present invention relates generally to security devices for use in combination with a safety line for preventing the fall of workers and, more particularly, to a security device formed of pivotally joined members held together by removable members which engage the device to provide a stable structure for supporting large loads.
2. Description of the Prior Art
Security devices are now commonly used by workers working in elevated positions, such as those employed on movable scaffolds. In order to prevent a worker from falling from a scaffold or work platform, a personal safety line is provided suspended from a position above the worker. The security device for attachment to the safety line is used in conjunction with a safety belt or harness fastened about the worker, and a lanyard is secured between the safety belt or harness and the security device. Typically, the lanyard is relatively short, and is provided with sufficient length to allow the worker some freedom of movement in the horizontal direction. In addition, the security device is generally freely movable up and down the safety line as the worker slowly moves up and down relative to the safety line. However, if the worker should suddenly fall, the lanyard will cause the security device to firmly grip the safety line and thereby prevent the worker from falling.
Security devices typically used include at least two separable parts whereby the security device may be opened to allow insertion and removal of the safety line. For example, U.S. Pat. Nos. 4,077,094, 4,560,029 and 5,156,240 all disclose security devices which may be opened to facilitate safety line insertion and removal. Unfortunately, as a result of providing devices having movable parts for securing the device about a safety line, the structural integrity of the device may suffer. For example, the hinged device disclosed in U.S. Pat. No. 4,560,029 may deform when it is used to stop the fall of a worker. Similarly, the device disclosed in U.S. Pat. No. 4,077,094 may be subject to similar problems in that this device discloses a pivoted member held in place on a U-shaped housing by a pin passing through one end of the pivoted member and through the U-shaped housing, and held in position at an opposite end of the pivoted member by a single pivot pin passing through one side of the housing and the pivoted member. In this structure the applied forces are carried by the pivoted member and are transmitted from the pivoted member to the U-shaped frame through the connecting pin members. Such an indirect transfer of forces through a security device is generally undesirable.
U.S. Pat. No. 5,156,240 also discloses a security device wherein a U-shaped housing is adapted to cooperate with a movable member of the device. This device has proven to be difficult to use in that in order to open the device, a pin must be removed and the movable member pivoted and moved longitudinally parallel to the axis of the safety line. Such a device may be difficult for a worker to manipulate quickly in order to efficiently attach the device to a safety line.
Accordingly, there is a need for a security device which may be attached to a safety line quickly and easily. In addition, there is a need for such a security device wherein the frame structure for the device is structurally configured to resist large deformation forces applied by a load hanging from the device.